The present invention relates to gas turbine engine casings, particularly gas turbine engine fan casings and turbine casings, more particularly to an improved blade containment assembly for use within or forming a part of the gas turbine engine casing.
Turbofan gas turbine engines for powering aircraft conventionally comprise a core engine, which drives a fan. The fan comprises a number of radially extending fan blades mounted on a fan rotor enclosed by a generally cylindrical, or frustoconical, fan casing. The core engine comprises one or more turbines, each one of which comprises a number of radially extending turbine blades enclosed by a cylindrical, or frustoconical, casing.
There is a remote possibility with such engines that part, or all, of a fan blade, or a turbine blade, could become detached from the remainder of the fan or turbine. In the case of a fan blade becoming detached this may occur as the result of, for example, the turbofan gas turbine engine ingesting a bird or other foreign object.
The use of containment rings for turbofan gas turbine engine casings is well known. It is known to provide generally cylindrical, or frustoconical, relatively thick metallic containment casings. It is known to provide generally cylindrical, or frustoconical, locally thickened, isogrid, metallic containment casings. It is known to provide strong fibrous material wound around relatively thin metallic casings or around the above mentioned containment casings. In the event that a blade becomes detached it passes through the casing and is contained by the fibrous material.
However, the relatively thick containment casings are relatively heavy, the relatively thin casings enclosed by the fibrous material are lighter but are more expensive to manufacture. The relatively thick casings with fibrous material are both heavier and more expensive to manufacture.
Accordingly the present invention seeks to provide a novel gas turbine engine casing which overcomes the above mentioned problems.
Accordingly the present invention a gas turbine engine blade containment assembly comprising a generally cylindrical, or frustoconical, casing, the casing being arranged in operation to surround a rotor carrying a plurality of radially extending rotor blades, and at least one corrugated metal sheet surrounding the casing, wherein the corrugations of the at least one corrugated metal sheet extend with axial and/or circumferential components. The at least one corrugated metal sheet may comprise at least one corrugated metal ring. Alternatively the at least one corrugated metal sheet comprises at least one corrugated metal sheet wound into a spiral.
Preferably the casing is a fan casing and the rotor blades are fan blades.
Alternatively the casing may be a turbine casing and the rotor blades are turbine blades.
Preferably the corrugations are equi-spaced.
The corrugations in the at least one corrugated metal sheet may extend with purely axial components. The corrugations in the at least one corrugated metal sheet may extend with purely circumferential components. Preferably the corrugations in the at least one corrugated metal sheet extend with both axial and circumferential components.
The casing may comprise a single corrugated metal sheet wound into a ring.
The casing may comprise a plurality of corrugated metal sheets, each of which is wound into a ring.
The corrugations in different corrugated metal sheets may be arranged to extend at different angles.
The corrugations in a first corrugated metal sheet may be arranged to extend with purely axial components and the corrugations in a second corrugated metal sheet are arranged to extend with purely circumferential components.
The corrugations in a first corrugated metal sheet may be arranged to extend with purely axial components and the corrugations in a second corrugated metal sheet are arranged to extend with axial and circumferential components.
The corrugations in a first corrugated metal sheet may be arranged to extend with purely circumferential components and the corrugations in a second corrugated metal sheet are arranged to extend with axial and circumferential components.
Preferably the corrugations in a first corrugated metal sheet are arranged to extend with axial and circumferential components and the corrugations in a second corrugated metal sheet are arranged to extend with axial and circumferential components.
The at least one corrugated metal sheet may be provided with apertures therethrough to attenuate noise.
The casing may comprise a single corrugated metal sheet wound into a spiral.
The casing may comprise a plurality of corrugated metal sheets, each of which is wound into a spiral.
The corrugations in different metal sheets may be arranged to extend at different angles.
The corrugations in a first corrugated metal sheet may be arranged to extend with purely circumferential components and the corrugations in a second corrugated sheet are arranged to extend with purely axial components.
The corrugations in a first corrugated metal sheet may be arranged to extend with purely circumferential components and the corrugations in a second corrugated metal sheet are arranged to extend with both axial and circumferential components.
The plurality of corrugated metal sheets define spaces therebetween, the spaces may be filled with an energy absorbing material to increase the blade containment capability of the casing.
The plurality of corrugated metal sheets wound into spirals define spaces therebetween, the spaces may be filled with an energy absorbing material to increase the blade containment capability of the casing.
The at least one corrugated metal sheet wound into a spiral defines spaces therebetween, the spaces may be filled with an energy absorbing material to increase the blade containment capability of the casing.
Preferably the at least one corrugated metal sheet is formed from titanium, an alloy of titanium, aluminium or steel.